Liquid cooling is a thermal management method that uses a circulating coolant (typically a water-glycol mixture or dielectric fluid) to remove heat from electrical and electronic components. In EV charging, liquid cooling is most commonly used in high-power DC charging to keep power electronics and charging cables within safe temperature limits, enabling higher continuous current, improved reliability, and longer component life.
What Is Liquid Cooling?
Liquid cooling transfers heat away from hot components by moving a coolant through:
– Cold plates or heat exchangers attached to power modules (IGBT/MOSFET stages, rectifiers, DC/DC)
– Liquid-cooled charging cables and connectors in high-current systems
– A pump, reservoir, filters, and a radiator or liquid-to-air heat exchanger
Because liquid has higher heat capacity than air, it can remove more heat with less airflow and less noise than purely air-cooled designs.
Why Liquid Cooling Matters in EV Charging Infrastructure
As charging power increases, thermal limits become a primary constraint. Liquid cooling helps:
– Sustain high continuous power without frequent derating
– Reduce thermal stress on components, improving uptime and service life
– Enable thinner, more flexible cables at high current by cooling the conductor and connector area
– Improve performance in hot climates or enclosed installations where airflow is restricted
For operators, better thermal stability often translates to higher station availability and more predictable charging performance.
How Liquid Cooling Works in Charging Systems
A typical liquid-cooling loop in a charging system includes:
– Heat generated by power electronics and/or the cable is absorbed into a cold plate or cooling channel
– A pump circulates coolant through the loop
– Heat is rejected via a radiator/heat exchanger (liquid-to-air or liquid-to-liquid)
– Sensors monitor temperature, flow rate, and pressure
– The charger control system adjusts fan speed, pump speed, or charging current to maintain safe limits
If cooling performance drops (low flow, high temperature), the charger may apply power throttling to prevent overheating.
Liquid-cooled cables in DC fast charging
Liquid cooling is especially relevant for high-current DC charging cables:
– Higher current causes resistive heating in conductors and connector pins
– Liquid-cooled cables can carry more current continuously with manageable temperatures
– This supports higher power delivery without making the cable excessively thick or heavy
In many high-power installations, liquid-cooled cables are a key enabler for stable fast charging sessions.
Key Benefits of Liquid Cooling
– Higher continuous power capability with less thermal derating
– Improved reliability of power modules and connectors through lower peak temperatures
– Reduced fan noise and lower dependence on high airflow
– More compact power electronics design in high-density systems
– Better performance under high ambient temperatures and heavy utilization
Limitations and Design Considerations
Liquid cooling adds complexity compared to air cooling:
– More components: pump, reservoir, hoses, seals, heat exchanger
– Maintenance needs: leak checks, coolant quality monitoring, filter replacement
– Risk management: leak detection, corrosion control, freeze protection
– Environmental requirements: coolant selection, disposal, and compatibility with materials
For outdoor chargers, designs must account for freezing conditions and long-term durability of hoses and connectors.
Related Glossary Terms
Thermal management
Power throttling
DC fast charging
Liquid-cooled cable
Heat exchanger
Charger derating
Uptime
Cooling methods